Weight Control and Diet

Description

Alternative Names

Weight Management

There are many approaches to dieting and many claims for great success with various fad diets. They include calories restriction, low-fat/high-fiber, or high protein and fat/low carbohydrates. Some evidence suggests that people may respond differently to specific diets depending on whether their weight is overly distributed around the abdomen or not. According to a 2003 report comparing four major diets (Atkins, the Zone, Ornish, and Weight Watchers), any healthful diet that achieves weight loss helps the heart. To date, although many diets achieve effective immediate weight loss, none has emerged as an effective tool for maintaining healthy weight. The only definite recommendation that can be made about any diet plan is to be sure to include an exercise program, assuming there are no health problems to preclude it.

The original "Four Food Groups" has been replaced with the "Food Guide Pyramid". This illustrates the relative proportions of different foods that make up a nutritious, well-balanced diet.

Calorie Restriction

Calorie restriction has been the cornerstone of obesity treatment. The standard dietary recommendations for losing weight are the following:

• As a rough rule of thumb, one pound of fat equals about 3,500 calories, so one could lose a pound a week by reducing daily caloric intake by about 500 calories a day. Naturally, the more severe the daily calorie restriction, the faster the weight loss. Very-low calorie diets have also been associated with better success, but extreme diets can have some serious health consequences.
• To determine the daily calories requirements for specific individuals, multiply the number of pounds of ideal weight by 12 to 15 calories. The number of calories per pound depends on gender, age, and activity levels. For instance, a 50-year old woman who wants to maintain a weight of 135 pounds and is mildly active might require only 12 calories per pound (1,620 calories a day). A 25-year old female athlete who wants to maintain the same weight might require 25 calories per pound 2,025 (calories a day).
• Fat intake should be no more than 30% of total calories. Most fats should be in the form of monounsaturated fats (such as olive oil). Saturated fats (found in animal products) should be avoided.

Low-Fat and High-Fiber Diets

Some studies suggest that replacing foods high in fats with low-fat complex carbohydrates (fruits, vegetables, and whole grains) may be more effective than calorie counting, particularly in maintaining weight loss. This dietary approach requires counting only grams of fat with the goal of achieving 30% or fewer calories from fat. (One gram of fat contains nine calories while one gram of carbohydrates or protein has only four calories, and dietary fat converts more readily to fat in the body than carbohydrates or proteins.) Simply switching to low-fat or skimmed diary products may be sufficient for some people.

There are possible drawbacks to this approach, however:

• Some people who reduce their fat intake may not consume enough basic nutrients, including vitamins A and E, folic acid, calcium, iron, and zinc. People on low-fat diets should consume a wide variety of foods and take a multivitamin if appropriate. Calcium deficiencies may be particularly harmful in women at risk for osteoporosis.
• Many people over-increase their intake of carbohydrates, believing that they are not adding calories. No one should use a low-fat diet as an excuse for over-consuming carbohydrates, particularly starchy foods and sugar. A high-calorie diet from any source will add pounds.
• Replacing fatty foods, such as cakes, cookies, and chips, with their commercial "low-fat" counterparts does not constitute a low-fat diet. These foods generally contain more sugar and hence calories, not to mention other ingredients, which have virtually no nutritional value. In fact, a 2002 study suggested that increasing sugar may, over time, reduce levels of HDL cholesterol, the so-called good cholesterol.
• Very low-fat diets may increase the risk for stroke from hemorrhage in the brain.

Some fat in a diet is essential. It should be derived from plant oils and fish, however, and not from saturated fat from animal products or trans-fatty acids from hydrogenated (hardened) oils. (Trans-fatty acids, in fact, are more of a risk factor for obesity than saturated fats, although both should be avoided.)

Fiber and Complex Carbohydrates. In all cases, complex carbohydrates found in whole grains and vegetables are preferred over those found in starch-heavy foods, such as pastas, white-flour products, and potatoes. Fiber is an important component of many complex carbohydrates. Fiber is almost always found only in plants, particularly vegetables, fruits, whole grains, nuts, and legumes (beans and peas). (One exception is chitosan, a dietary fiber made from shellfish skeletons.) Fiber cannot be digested but passes through the intestines, drawing water with it and is eliminated as part of feces content. The following are specific advantages from high-fiber diets (up to 55 grams a day):

• Insoluble fiber (found in wheat bran, whole grains, seeds, nuts, and fruit and vegetable peels) has been associated with weight loss. Studies also suggest that diets rich in fiber from whole grains reduce the risk for type 2 diabetes.
• Soluble fiber (found in dried beans, oat bran, barley, apples, citrus fruits, and potatoes) has important benefits for the heart, particularly for achieving healthy cholesterol levels and possibly benefiting blood pressure as well. Simply adding breakfast cereal to a diet appears to reduce cholesterol levels. People who increase their levels of soluble fiber should also increase water and fluid intake.

High-Protein Diets

High-protein diets, such as the Atkins and South Beach diets, are proving to be very effective in producing short-term weight loss. Because of their emphasis on fats and proteins, many experts are concerned about long-term health problems. Still, significant studies are reporting benefits on cholesterol and blood sugar levels. Centers that promote this approach argue that heart problems from obesity are due to insulin disturbances from sugar imbalances. Therefore, they believe that restricting carbohydrates is the best approach for obesity--and especially for overweight people with diabetes. More research is needed, however, to determine the long-term impact on health.

High-Protein, Low-Carbohydrate Diets. High-protein, low-carbohydrate diets have become popular again. They include Dr. Atkins, Protein Power, Sugar Busters, and Dr. Stillman. The Atkins diet is currently among the most popular and has a four-phase program:

• Induction. For the first two weeks, individuals consume no more than 20 grams of carbohydrates a day (no fruit, bread, grains, starchy vegetables, or dairy products other than cheese, cream or butter.) They eat pure protein and fats. (This phase is not suitable for children, pregnant women, or anyone with kidney disease.)
• On-going Weight Loss. After the first phase, individuals continue to lose weight while they increase carbohydrate levels by five grams each week.
• Premaintenance. When individuals get close to their weight goal, they add another 10 grams of carbohydrates per week as long as they do not begin to gain weight. Weight loss is very slow at this time, but the individual is now getting used to maintenance.
• Maintenance. Lifetime maintenance is usually between 40 and 100 grams of carbohydrates a week, depending on steady weight level.

Studies are reporting effective short-term weight loss with the diet, although it is not clear if the high-protein diet is any better than low-fat diets for maintaining the weight loss. Contrary to expert expectations, this diet also may have some important heart benefits. Studies in 2002 and 2003 have indicated that the diet lowers blood glucose levels, which can be important in people who are diabetic. The diet also reduces triglycerides (unhealthy fat molecules) and increases HDL (so-called good cholesterol) levels. High triglyceride and low HDL levels are important risk factors for heart disease and common in people with type 2 diabetes. Studies are mixed on whether the diet reduces overall cholesterol or LDL (the bad) cholesterol.

Anyone who chooses this diet should prefer fish or soy products to meat as protein sources. Fish may reduce leptin, a hormone associated with fat storage and heart diseases, and would be the best protein source. People on this diet should also choose monounsaturated fats (as in olive oil) over saturated fats or trans-fatty acids fat. Patients often need supplements, at least a multivitamin and possibly calcium, chromium, omega-3 fatty acids (found in fish oil), and other supplements.

One negative byproduct of this diet is the release of substances called ketones, which can cause nausea, lightheadedness, and bad breath. Long-term effects on health are still unknown in people who continue to adhere to it. For example, the Atkins diet restricts some vegetables and most fruits that are known to protect against serious diseases--not only heart problems, but also cancer. The diet also may produce excessive calcium excretion in urine, which can increase the risk for kidney stones and osteoporosis. In any case, high-protein intake, particularly from meat, can be harmful in people with kidney problems. Individuals at risk for kidney stones or who have other kidney problems should not go on high-protein diets without consulting their physicians. Unfortunately, many people with diabetes are subject to kidney problems, which could negate any possible benefits for them. A high meat intake has also been associated with certain common cancers, notably prostate and colon cancers. A 2002 study suggested that such diets during pregnancy may increase the risk for high blood pressure in the offspring.

High-Protein, Favorable Carbohydrates. High-protein diets, such as the South Beach Diet and the Zone, encourage healthy fats but also allow favorable carbohydrates. For example the Zone uses healthy carbohydrates (vegetables, dried beans) and unsaturated fats. The South Beach diet uses carbohydrates with low-glycemic index scores. These are selected foods containing carbohydrates that delay the increase in blood sugar after a meal compared to other foods. Low-glycemic foods include barley, dried bean and peas, milk, strawberries, and apples. High-glycemic foods include refined grains, white bread, white potatoes, and bananas and other tropical fruits. The glycemic index was developed for use in diabetes--not for weight loss. Nevertheless, there is some evidence that foods with low glycemic indexes may produce a feeling of fullness and so discourage further eating. As with any high-protein diets, people at risk for kidney stones or have other kidney problems should avoid these plans.

Liquid Meal Replacements

Some studies have reported good success with meal replacement beverages (Slim-Fast, Sweet Success). They contain major nutrients needed for daily requirements; each serving typically contains between 200 to 250 calories and replaces one meal. (Using them for all meals reduces calories to a severe extent and can be harmful.) One study reported that most subjects who had undergone a 12-week weight loss program and then used Ultra Slim Fast supplements as directed for maintenance kept off more than half their weight loss after more than three years. A quarter of the subjects were still losing weight.

Support Groups and Behavioral Approaches

Commercial and Non-Profit Support Programs for Weight Loss. This report cannot possibly address the many commercial and nonprofit weight-loss programs currently available or assess their claims. Taking off Pounds Sensibly (TOPS), a nonprofit support organization with many local chapters, is the least expensive program, costing $20 a year. Most of the commercial programs, such as Weight Watchers, Jenny Craig, and NutriSystem offer individual or group support, lifestyle changes and packaged meals. These programs tend to be expensive. There are few well-conducted studies on these programs. One 2003 study reported modest weight loss over two years with Weight Watchers compared to a self-help program. (There were no differences in heart risk factors).

Cognitive Behavioral Approaches. Most support programs use some form of cognitive-behavioral methods to change the daily patterns associated with eating. They are very useful for preventing relapse after initial weight loss. The following is a typical approach may work as follows:

• The patient first records in a diary all activity related to eating patterns, including the times of day, length of meal, emotional states, companions, and, of course, the kind and amounts of food eaten. (Most people--even professional dieticians according to one study -- tend to underreport their daily calorie intake, but it is still a good method for increasing their awareness of eating patterns.) One patient said that recording circumstances surrounding relapses was a particularly valuable guide for understanding the stresses leading to her own eating behaviors.
• The patient reviews the diary with a therapist or group to set realistic goals and identify patterns that the patient can change. For instance, if food is normally eaten while watching television, then the patient may be advised to eat in another room instead.
• Good eating habits are reinforced by rewards, other pleasures that substitute for high calorie consumption and sedentary activities.

Behavioral modification has been shown to be helpful particularly for people who have an overly strong response to the taste, smell, and appearance of food. It also may be useful for binge eaters.

Stress-Reduction Techniques. Stress reduction and relaxation techniques may be helpful for some people with obesity, such as those whose weight is related to night-eating syndrome. [For information on such techniques, see Well-Connected Report #31 Stress.]

Changing Sedentary Habits and Exercise

Changing Sedentary Habits. Making even small changes in physical activity can expend energy. For example, simply getting up to turn on and off the TV instead of using the remote and standing while talking on the phone may drop up to five pounds a year. Other suggestions include cooking ones own food (instead of eating take out or fast food), walking to as many places as possible, using stairs instead of escalators or elevators, and gardening. Even fidgeting may be helpful in keeping pounds off, and, in one study, chewing gum increased energy expenditure. No one should rely on such mild activities, however, for serious weight loss. Only high levels of physical activity -- not just using up energy -- help prevent obesity.

Approach to Exercise. Exercise, which replaces fat with muscle, is the critical companion for any weight control program. In a one-year study, women who regularly averaged 3.5 days (176 minutes) of exercise each week lost significantly more weight than women who did not exercise regularly. Women who exercised more than 195 minutes a week lost nearly 7% of their abdominal fat.

People who exercise are more apt to stay on a diet plan. Exercise improves psychological well-being and replaces sedentary habits that usually lead to snacking. Exercise may even act as a mild appetite suppressant. Moreover, exercise improves overall health even with modest weight loss. In support of this, a British study found that overweight fit individuals had half the death rate of unfit trim individuals.

Be forewarned, however, that the pounds wont melt off magically. Losing significant weight requires both intensive exercise and calorie restriction. In addition, if a person exercises but doesn't diet any actual pounds lost may be minimal because dense and heavier muscle mass replaces fat. Nonetheless, regardless of weight loss, a fit body will look more toned and be healthier. In addition, exercise benefits the heart even with modest weight loss.

The following are some suggestions and observations on exercise and weight loss:

• The more strenuous the exercise, the better the chances for short- and long-term success. With intense exercise, the metabolism continues to burn calories before returning to its resting level. This state of elevated metabolism can last for as little as a few minutes after light exercise to as long as several hours after prolonged or heavy exercise.
• The treadmill burns the most calories of standard aerobic machines. It may be particularly effective when used in short multiple bouts during the day. In fact, exercise sessions as short as 10 minutes in duration that are done frequently (about four times a day) may be the most successful program for obese people.
• Resistance, or strength, training is excellent for replacing fat with muscles. It should be performed two or three times a week.
• As people slim down, their initial level of physical activity becomes easier and they burn fewer calories per mile of walking or jogging. The rate of weight loss slows down, sometimes discouragingly so, after an initial dramatic head start using diet and exercise combinations. People should be aware of this phenomenon and keep adding to their daily exercise regimen.
• As people age, they also need to exercise more to keep off the same amount of weight.
• Changes in fat and muscle distribution may differ between men and women as they exercise. Men tend to lose abdominal fat (which lowers their risk for heart disease faster than reducing general body fat). Exercise, however, does not appear to have the same effect on weight distribution in women. In one interesting study women who underwent aerobic and strength training lost fat in their arms and trunk, but did not gain muscle tissue in these regions. On the other hand, they gained muscles but achieved no change in fat mass in their legs.

Warning Note. Because obesity is one of the risk factors for heart disease and diabetes, anyone who is overweight must discuss their exercise program with a physician before starting. Sudden strenuous exercise, in such cases, can be very dangerous.[For more information, seeWell-Connected Report #29 Exercise.]